There’s permanent storage that doesn’t need any power and lasts forever.
Your computer likely has a tiny battery for important things like clock time which should last for a very long time.
Your computer probably has code that dumps all memory contents to permanent storage just before the battery runs out and reads it back when there is enough battery life.
Why does [burst mode (fast access to multiple elements from the same row)] not exist for columns?`
There are different "dimensions" involved with varying the basic rectangular semiconductor memory:
invest extras in one place, e.g., separate data in&out vs. shared.
invest extras in one line along one of the dimensions of the cell array.
Conventional RAM is organized in rows and columns. The CPU selects one row, then the RAM hardware gathers all cells in columns within that row and delivers them to the CPU.
If you were able to also select a column and gather all cells within that column, you would get a different set of bits. No guarantee that they are ordered in any useful way for you. No ...